Solid-state electrical energy meters, also referred to as “watt-hour meters,” are used on a widespread basis in commercial and industrial applications. Solid-state meters offer advantages in relation to conventional electromechanical electrical-energy meters. For example, solid-state electrical-energy meters can incorporate features that offer programmability, as well as flexibility in tailoring the various functions of the meter to a particular user, without substantially increasing the overall cost of the meter.
The use of solid-state electrical-energy meters in residential applications has not progressed to the extent of commercial and industrial use. In particular, typical residential applications do not require the comparatively high degree of functionality called for in many commercial and industrial applications. Hence, the cost advantages offered by solid-state meters in relation to programmability and functionality, in general, are not as significant in residential applications as they are in commercial and industrial applications.
The demand for greater programmability and functionality in residential electrical-energy meters, however, is increasing. Hence, the demand for solid-state electrical-energy meters in residential applications is expected to increase dramatically in the near future. The manufacturing costs of solid-state meters, however, need to be comparable to or lower than those of electro-mechanical meters in order for solid-state meters to compete successfully in the residential-use market. Moreover, any electrical-energy meter intended for residential use must comply with the applicable requirements of the American National Standards Institute (ANSI) to ensure compatibility with existing power-distribution networks.
Conventional electrical-energy meters of both the electro-mechanical and solid-state type typically incorporate a relatively large number of fasteners, e.g., screws, rivets, eyelets, pins, etc., to secure the various components thereof. These fasteners increase the overall parts count and the assembly time of the meter, and thus raise the manufacturing cost thereof.
Moreover, the base and other components of conventional electrical-energy meters are usually formed from thermosetting plastics. Thermosetting plastics are relatively hard and brittle, and thus are not well suited to withstand the impact loads that electrical-energy meters are typically exposed to during shipping and installation. Hence, components manufactured from these types of materials must have relatively large cross sections to provide the components with sufficient resistance to the anticipated impact loads. This requirement increases the manufacturing cost of the meter. Moreover, the brittle quality of thermosetting plastics precludes the use of cost-effective design features that require resilient components.
Consequently, a need exists for a solid-state electrical-energy meter for residential applications that has a comparatively low cost, and complies with the applicable ANSI requirements.